S6148 Methotrexate-Associated Lymphoproliferative Disorder Isolated to the Small Bowel Resulting in Bowel Obstruction

Introduction: Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a rare but serious complication of methotrexate (MTX) therapy, characterized by histopathologically observed lymphoid proliferations that may affect various organ sites. However, isolated involvement of the GI tract, specifically the small bowel, is exceedingly rare. We present a patient on MTX therapy who developed MTX-LPD confined to the small bowel, subsequent anemia, retention of video capsule, and small bowel obstruction (SBO) due to an MTX-LPD-associated stricture requiring surgical resection and retrieval. Case Description/Methods: A 72-year-old man with a history of renal cell carcinoma post-nephrectomy and psoriasis on MTX presented with iron deficiency anemia. Bidirectional endoscopy was unrevealing for cause of anemia, so capsule endoscopy was performed. Several days after ingesting the capsule, the patient reported that it had failed to pass and presented to the hospital with nausea and vomiting. Imaging demonstrated a retained capsule and developing SBO. Colonoscopy with deep ileoscopy was attempted to retrieve the capsule, but revealed a 2 cm long × 3 mm in diameter deep ileal stricture. Attempts were made to traverse it after dilation but was unsuccessful. The area was biopsied and tattooed. He subsequently underwent a small bowel resection, which identified a stricture about 40 cm proximal to the ileocecal valve. Histopathology report revealed Epstein-Barr virus+ polymorphic LPD in the setting of MTX therapy, consistent with iatrogenic immunodeficiency-related LPD with Hodgkin-lymphoma-like features. Pathology was confirmed at multiple institutions. Differentials included Epstein-Barr virus+ polymorphic B-cell LPD vs Epstein-Barr virus+ mucocutaneous ulcer. PET-computed tomography was negative. He was referred to oncology. MTX was discontinued and recommended to undergo double-balloon enteroscopy to evaluate for additional small bowel involvement. The patient is now asymptomatic. Discussion: MTX-LPD is a rare complication of MTX therapy, with increased risk seen in patients with rheumatoid arthritis and psoriasis. Approximately 40%-50% of MTX-LPD cases occur at extranodal sites such as the skin, salivary glands, lungs, gastrointestinal tract, liver and spine. Isolated GI involvement is even more rare and rarely necessitates surgical intervention. About half of MTX-LPD cases respond to discontinuation of MTX alone, while the remainder require chemotherapy. With this case, we aim to raise awareness to a unique presentation of MTX-LPD within the field of gastroenterology.